51015

Steel anode baskets are gassing in tank  

January 21, 2009

my cy copper tank. what would cause iron baskets to gas when rectifier is not on. I have changed my baskets to titanium baskets now my tank will not plate copper it plates a silver color. I have disconnected neg-positive from rectifier and now anodes are gassing. this is a new solution my tanks are poly. I have taken heater, filter and disconnected all power supply from tank and these anodes or iron baskets are still gassing.HELP Please

Henry McCloskey
plating shop owner - New Orleans,La

Henry,
You seemed to have ruled out all equipment failures. I would make sure you are using high purity, oxygen free copper anodes in the bath. I used to stagger the copper anode baskets with steel anodes so the copper content in the bath does not build up too fast. It sounds to me you have severe case of immersion plating here. Something in the solution is way out of whack. I would perform a complete analysis on the bath. My gut feeling is the copper is way too high, or the free cyanide concentration is way out of spec. I don't know if this is a sodium or potassium based bath, make sure the NaOH or KOH is in spec as well. Hope this helps you.

Mark Baker
Fellow plater - Syracuse, N.Y.

You cannot use titanium baskets in a cyanide solution. The titanium anodizes and will not pass current.

Robert H Probert Robert H Probert Technical Services Garner, North Carolina Editor's note:        Mr. Probert is the    author of Aluminum How-To / Aluminio El Como

Hallo Henry,

Don't be so surprised, it is quite normal. There's galvanic link between copper and iron resulting in gassing on iron. In cyanide bath iron is more noble metal than copper, therefore copper is dissolving and iron is gassing with hydrogen. The more bigger surface of links the more hydrogen. You use baskets, so the surface is very big. And it's a big mistake to use iron baskets in cyanide copper plating, because in cyanide solution iron is noble but not passive. It will make oxidation of cyanides and dissolution of copper up to excess. The right solution are titanium or plastic baskets or no baskets. Why you observed white color after changing baskets into titanium ones, I can't guess. Probably your bath has been contaminated. Iron baskets were really wrong solution, but I can ensure that titanium ones would be right.
Best regards

JANUSZ LABEDZ
- WARSAW, POLAND